Low-cost capacitive sensor for detecting palm-wood moisture content in real-time

In this study, we analyze a non-invasive and low-cost wood moisture meter by means of a capacitive detection circuit. The process of the design and development of an oil-palm-wood moisture meter is described. As part of the study, two electrode structures, i.e., parallel-plate and coplanar electrodes, are tested. The capacitive detection circuit includes a square-wave-generator circuit, low-pass filter circuit, and signal-conditioning circuit. The frequencies of the square-wave excitation signal are in the range of 200 kHz and are analyzed via a microcontroller to interpret the percentage of oil-palm-wood moisture content. The applicability of the capacitive moisture measurement is investigated under various moisture conditions of the oil palm wood i.e., 5%-20%. The experimental results show that the measurement accuracy of the detection circuit is high, with an acceptable measurement error.